1. Field of the Invention
The invention relates to a method of adjusting the height of a nip between an adhesive applicator roll and a nip roll of an adhesive applicator apparatus for a web of corrugated board, and to an adhesive applicator apparatus for putting the method into practice.
2. Background Art
When a single-face lined web of corrugated board is to be provided with another liner on its non-faced side, then glue must be applied to the tips of the corrugated web on the non-faced side. To this end, the single-face lined medium is led through the nip of an adhesive applicator, a so-called sizing press. In doing so, it is extraordinarily difficult to regulate the height of the nip in such a way that on the one hand the hydrodynamic pressure of the thin adhesive layer on the adhesive applicator roll is overcome for gluing of the tips of the corrugated web to take place, and that on the other hand the corrugated web will not be crushed and the tips are not overly loaded with glue by too low an adjustment of the height of the nip.
It is an object of the invention to embody a method of adjusting the height of a nip between an adhesive applicator roll and a nip roll of an adhesive applicator apparatus for a web of corrugated board and an adhesive applicator apparatus for putting the method into practice, by means of which to have optimal gluing of the tips of the corrugated web of a single-face lined web of corrugated board.
According to the invention, this object is attained by a method including the following steps: conveying, through the nip, the web of corrugated board, which at least includes a liner web and a corrugated web with tips turned away from the liner web; applying an adhesive on the tips of the corrugated web by means of the adhesive applicator roll, with the liner web bearing against the nip roll; and pressing the web of corrugated board by a given constant force between the adhesive applicator roll and the nip roll. This object is further attained by an adhesive applicator apparatus comprising a frame; an adhesive applicator roll, which is disposed in the frame and drivable in rotation about a central longitudinal axis; a nip roll, which is disposed in the frame and drivable in rotation about a central longitudinal axis; a nip between the adhesive applicator roll and the nip roll for a web of corrugated board to pass through, which comprises at least one liner web and a corrugated web; a force sensitive device for detection of an actual force which acts vertically on the web of corrugated board in the nip; a distance adjusting device for modification of the height of the nip by displacement of the rolls relative to each other substantially on a plane that is spanned by the central longitudinal axes; and a control unit for comparison of the actual force with a given nominal force in the nip and for triggering the distance adjusting device. The actual force required in the nip for optimal gluing of the tips of the corrugated web is determined empirically.